EP0352928B2 - I.V. catheter with self-locating needle guard - Google Patents

Abstract

An I.V. catheter is described, including a catheter and hub assembly (15, 16, 18) and a needle and hub assembly (12, 20). A needle guard (30), including a tubular distal portion (32) and a split proximal flange (34), is located about the needle (12) at the distal end of the needle hub (20). The needle (12) includes a slot (50) near the needle tip. As the needle assembly (12, 20) is withdrawn from the catheter (15), the needle guard (30) slides along the needle (12) until the split flange (34) engages the needle slot (50), which locks the tubular distal portion (32) of the guard (30) over the needle tip.

Description

• This invention relates to intravenous (I.V.) catheters and, in particular, to I.V. catheters which cover the cannula tip after use to prevent accidental injury from used needles.
• Intravenous catheters for the infusion of fluids into the peripheral veins of a patient are one of the most common devices used in I.V. therapy. I.V. catheters may be produced in two general forms: through-the-needle catheters, in which a catheter is threaded through the needle cannula and into the vein of a patient, and over-the-needle catheters, in which the needle and concentric outer catheter are inserted into the vein and the needle is withdrawn through the emplaced catheter.
• A typical over-the-needle I.V. catheter requires the user to remove and then dispose of a contaminated needle after the needle tip and catheter are properly located in the vein of the patient. Once the needle is withdrawn from the catheter, the user's immediate priorities are infusion set connection and site preparation, including the taping of the catheter to the patient. Because of the urgency of these procedures, the needle is normally just dropped conveniently nearby and then retrieved later. Since the needle at this time is exposed and located close to where the user is completing work with the catheter, accidental self-inflicted needle injuries are not uncommon. For reasons of the desirability of protecting the user from exposure to hepatitis and AIDS, there is an increasing need to protect the user from accidental needle injury.
• A catheter design which is directed toward this need is shown in United States patent no.4762516. The catheter shown in this application includes an elongate body which houses a sliding needle guard. As the needle is withdrawn from the emplaced catheter, the user pushes the tab at the distal end of the needle guard, thereby sliding the needle guard out of the housing and along the needle, until the distal end of the guard covers the needle tip and the proximal end of the guard locks in the housing. The needle and guard may then be set aside with the needle tip fully protected.
• While the arrangement described in this patent application provides full protection against accidental needle injury, the requirement of a sliding needle guard which exceeds the length of the needle necessarily requires a rather long and bulky assembly. Moreover, since the user must push the guard tab along the full length of the needle before the guard will lock in place over the needle tip, the arrangement is somewhat cumbersome to operate for users with small hands and fingers.
• Accordingly it would be desirable for a needle to be securely protected by a small needle guard, and it would be most preferable for the needle guard to be moved into position over the needle tip automatically upon withdrawal of the needle from the patient, without the intervention of any special motion by the user.
• In accordance with the principles of the present invention, an I.V. catheter with a self-locating needle guard is provided. The needle guard is located about the needle at the jointure of the needle and needle hub. Prior to use of the catheter the guard, which is of sufficient length to cover just a distal portion of the needle, is located within the catheter hub. At its proximal end the tubular guard includes a split locking flange, which retains the guard within the interior of the catheter hub. The guard will remain within the catheter hub while the needle is withdrawn from the patient until the locking flange engages a slot located near the distal end of the needle. The guard will then lock in place over the needle tip as the needle is fully withdrawn from the catheter.
• In the drawings:
• FIGURE 1 illustrates an I.V. catheter in perspective and constructed in accordance with the principles of the present invention;
• FIGURE 2 illustrates the I.V. catheter of FIGURE 1 in partial cross-section without a needle guard;
• FIGURE 3 illustrates the cross-sectional view of FIGURE 2 with the needle guard in place in the catheter hub;
• FIGURE 4 illustrates the needle guard of FIGURE 3 in cross-sectional detail
• FIGURE 5 illustrates the needle guard when positioned at the proximal end of the needle; and
• FIGURE 6 illustrates the needle guard when locked at the distal end of the needle;
• FIGURE 7 illustrates in partial cross-section an alternate embodiment of the slotted I.V. catheter needle of the present invention; and
• FIGURE 8 illustrates in partial cross-section a slotted I.V. catheter needle arranged for prompt blood flash detection.
• Referring first to FIGURE 1, an I.V. catheter constructed in accordance with the principles of the present invention is shown. Thecatheter 10 comprises atube 15 made of fluorinated ethylene propylene or polyurethane material. Thetube 15 is tapered at its distal end where it may easily slide into an opening in the patient's body formed by ahollow needle 12. The proximal end ofcatheter tube 15 is concentrically affixed within the distal end of acatheter hub 16, 18. The dual diameter hub terminates at its proximal end in a tab or fitting 14, suitable for attaching the catheter hub to a tubing set which administers a source of intravenous fluid.
• Thecatheter 10 is engaged by thehollow needle 12, which is affixed at its proximal end to aneedle hub 20. Theneedle hub 20 is hollow and includes a proximally locatedflange 23. Molded to the flange is ahollow flash chamber 26, which is made of a transparent or translucent polymer such as polypropylene or polycarbonate. The proximal end of the needle terminates in thehub 20, just short of the flash chamber.
• Inserted into the flash chamber 26 (but shown separated just prior to insertion in FIGURE 1) is aflash plug 70. Theflash plug 70 is made of a polymeric material and will frictionally remain in place when inserted into the flash chamber. The flash plug body comprises a smaller diameterdistal end 72 sized for a frictional fit in theflash chamber 26, and a somewhat squareproximal end 74 with convex sides, which enables the flash plug to be easily grasped and inserted into the flash chamber. Theflash plug 70 is hollow with anaperture 76 extending completely through the flash plug body. The distal opening of theaperture 76 is visible in FIGURE 1. An insert made of a porous material is located within theaperture 76. The porous insert is pervious to the flow of air out of the flash chamber as the chamber fills with blood, but the pores of the insert are small enough to impede any blood flow therethrough.
• Referring next to FIGURE 2, thecatheter 15 and itshub 16, 18, and theneedle 12 andneedle hub 20 are shown in cross-sectional detail. The proximal end of thecatheter 15 is secured withinpassageway 17 of thedistal end 16 of the catheter hub by asleeve 40. Thesleeve 40 is positioned within the proximal end of the lumen of thecatheter 15. By forcingsleeve 40 into the lumen of the catheter, the sleeve effects an expansion of the proximal end of the catheter into contact with the internal surface of thepassageway 17, thereby locking the hub and catheter together to prevent axial movement therebetween. Thesleeve 40 is outwardly tapered at its proximal end to form aflange 42 which acts to securely position thesleeve 40 relative to thepassageway 17.
• Thehollow needle 12 extends from its distal tip through thecatheter 15 and sleeve 40, and into apassageway 27 in the center of theneedle hub 20. The proximal portion of theneedle 12 is affixed byepoxy 24 at the distal end of theneedle hub 20. The proximal end of theneedle 12 extends beyond the epoxy and into the passageway so that the lumen of the needle will not become filled with epoxy during the attachment procedure.
• Thedistal end 28 of theneedle hub 20 is of a lesser diameter than the major portion of the needle hub. This lesser diameter end is dimensioned to engage the open proximal end of thecatheter hub 18.
• In a conventional catheter and introducer needle assembly, the lesser diameter distal end of the needle hub is generally elongated and tapered to substantially occupy the proximal interior of the catheter hub. In the catheter assembly of the present invention, it may be seen that themajor portion 22 of the cavity within theproximal end 18 of the catheter hub is unoccupied, with only theneedle 12 extending through this region. The reason for reserving this space within the catheter hub is made clear with reference to FIGURE 3.
• In FIGURE 3 it may be seen that aneedle point guard 30 is located within the cavity of the catheter hub. FIGURE 4 is an enlarged cross-sectional view of theneedle point guard 30, which resembles a flanged cylinder. The cylindricaldistal portion 32 of the guard has an internal aperture with a diameter that enables theportion 32 to slide smoothly along theneedle 12. The inner diameter of thecylindrical portion 32 is thus just slightly larger than the outer diameter of the needle. At the proximal end of theguard 30 is acircular locking flange 34 with acentral aperture 36 that is concentric with that of thecylindrical portion 32. The diameter of theflange aperture 36 is slightly less than the outer diameter of theneedle 12. Theflange 34 and a proximal portion of thecylindrical portion 32 is slit horizontally by anexpansion slot 38. Theneedle point guard 30 is made of a flexible material so that the flange and cylindrical portion will flex open and closed again as described below.
• Referring concurrently to FIGURES 3 and 5, when the catheter and introducer needle are assembled prior to use, the needle point guard is slipped over the point of the needle to slide to a position adjacent the distal end of theneedle hub 20. Since theflange aperture 36 is slightly smaller than the outside diameter of the needle, the needle will spread the needle point guard open at theexpansion slot 38. The catheter and catheter hub are slipped over the needle until thehub 18 engages the distal end of the needle hub as shown in FIGURE 3. Theneedle point guard 30 is thereby enclosed within thecavity 22 of the catheter hub. The spreading of theflange 34 causes the top and bottom of the flange to engage the inner wall of the catheter hub, as indicated at 39. The needle point guard is thus snugly retained within thecatheter hub cavity 22. To ensure retention of the needle point guard within thecavity 22, it may further be desirable to form projections extending from the inner wall of the catheter hub just proximal the intended location of the guard, as indicated at 44.
• After the user has properly positioned the needle tip and distal end of the catheter within the artery or vein of a patient, as indicated by the presence of blood in the flash chamber, the needle and needle hub are withdrawn from the catheter in preparation for attachment of a tubing set to the catheter hub. As the needle is initially withdrawn, theneedle point guard 30 slides along the needle, but remains in position in thecavity 22 due to the engagement of theflange 34 and catheter hub at 39. Theneedle point guard 30 slides along the needle as shown in FIGURE 5. Finally, the needle is withdrawn so that anengagement slot 50 near the tip of theneedle 12 becomes aligned with theflange 34. At this moment theexpansion slot 38 of the guard springs closed as the rim of the flange aboutaperture 36 is captured in engagement with theslot 50. Since the flange is no longer spread it is no longer retained within the catheter hub, but will leave thecavity 22 in engagement with theneedle 12 andslot 50, as shown in FIGURE 6. The needle may then be safely set aside without danger of accidental injury.
• In an I.V. catheter constructed in accordance with the principles of the present invention, it may be desirable to insure that the initial "flash" of blood resulting from successful venipuncture be directed immediately through the needle lumen to theflash chamber 26, without any blood leakage out theengagement slot 50. To provide for this performance, theengagement slot 50 may be covered by athin membrane 52 as shown in FIGURE 7. The membrane may partially or completely surround theneedle 12 at the slot location. The membrane will seal the engagement slot to prevent blood leakage out of the needle at this point, but must be sufficiently flexible so that it will distend without rupturing as theguard flange 34 engages theslot 50. Theneedle point guard 30 will thus be securely engaged in theengagement slot 50 while themembrane 52 prevents any blood leakage through the slot.
• However, for some applications it may be desirable to take advantage of theopen engagement slot 50. The standard technique for venipuncture requires the practitioner to visualize blood in the needle hub flash chamber to ascertain that the needle tip and catheter are within the vessel. For small sizes of I.V. catheters the flash of blood is very small, and is inhibited from immediate visualization by the length of travel to the flash chamber. Moreover, there is the further distraction of having to avert one's vision between the venipuncture site and the flash chamber at the proximal end of the catheter. Accordingly it would be desirable to provide for more rapid detection of the blood flash, and to obviate the need for the practitioner to avert his vision from the venipuncture site.
• These objectives may be met by utilizing theslot 50 for early detection of even a small flash of blood. As shown in FIGURE 8, theslot 50 is located just proximal the needle tip and the tapereddistal end 19 of thecatheter 15. When the blood vessel is punctured the blood will flow up the lumen of the needle to theslot 50, where it will fill the slot cavity as shown at 54. The blood will then flow through the small space between theneedle 12 and thecatheter 15 as shown at 56. When this interlumenal blood flow extends beyond the skin line (indicated schematically by dashed line 60), the blood will be visible between the catheter and needle as shown at 58. This small flash ofblood 58 will thus be readily visible through the transparent or translucent catheter at the venipuncture site, indicating to the practitioner that the venipuncture was successful.
• It may be appreciated that the detection of blood flash in this manner obviates the need for the flash chamber at the proximal end of the needle hub. Consequently, blood leakage from a vented flash plug may be prevented. Furthermore, it is also not necessary for blood to fill the entire needle lumen which may if desired be blocked or terminated proximal theslot 50. Rapid detection of even a small blood flash is accordingly enhanced.
• From the foregoing description of the present invention, additional enhancements and modifications will be apparent to the user. For instance, to insure proper alignment between theengagement slot 50 and theflange 34 of the needle point guard, it may be desirable to form mating slots and projections in the inside of thecatheter hub 18 and the outer periphery of thedistal end 28 of theneedle hub 20 and theedges 39 of the needle point guard. By tracking the catheter components in this manner the longitudinal edges of theengagement slot 50 will be maintained in alignment with theexpansion slot 38 of the guard for assured engagement of the guard flange in the engagement slot.

Claims (11)

1. An intravenous (I.V.) catheter comprising:
      a catheter assembly including a catheter (10) attached to a hollow catheter hub (16, 18); and
      an introducer needle assembly, including a hollow needle (12) with a distal tip, said needle being affixed near its proximal end to a needle hub (20), the distal end of said needle hub being suitable for engaging said hollow catheter hub;
      characterised in that a needle guard (30) is provided, and in that
      said needle includes means (50) for engaging said needle guard (30), said needle guard (30) being suitable for confinement within said hollow catheter hub (18) and including a proximal portion having means (34) for engaging said engaging means (50) of said needle and a distal portion (32) for extending over said needle tip when said proximal portion (34) is engaged with said engaging means (50) of said needle.
2. The I.V. catheter of Claim 1, wherein said engaging means of said needle comprises an engagement slot (50) located near said distal tip of said needle.
3. The I.V. catheter of Claim 1 or Claim 2, wherein said distal portion (32) of said needle guard (30) comprises a cylindrical portion having an inner diameter slightly larger than the outer diameter of said needle.
4. The I.V. catheter of Claim 3, wherein said proximal portion of said needle guard comprises a flange (34) having a central aperture (36) aligned with said distal cylindrical portion (32), and said needle guard engaging means includes an axially aligned expansion slot (38) passing through said flange.
5. The I.V. catheter of Claim 4, wherein said needle guard (30) becomes locked in engagement with said needle when the rim of said flange aperture (36) engages said engagement slot (50) of said needle.
6. The I.V. catheter of Claim 4 or Claim 5, wherein the diameter of said flange aperture (36) is less than the outer diameter of said needle,
      whereby said needle spreads said flange (34) about said expansion slot when the full diameter of said needle passes through said flange aperture.
7. The I.V. catheter of any one of Claims 1 to 6, wherein said needle guard further includes means for retaining said needle guard within said catheter hub (18) prior to engagement of said needle engaging means and said needle guard engaging means.
8. The I.V. catheter of Claim 7, wherein said proximal portion of said needle guard comprises a radially extending flange (34) having a central aperture, and said retaining means includes an axially aligned expansion slot passing through said flange,
      whereby said flange is brought into contact (39) with said catheter hub when said expansion slot opens in response to the passage of said needle through said central aperture.
9. The I.V. catheter of any one of Claims 1 to 8, in which the hollow needle includes a slot (50) located in a wall thereof for passage of blood to the region (54, 56, 58) between said hollow needle and said catheter,
      whereby the presence of blood may be visually detected between said hollow needle and said catheter.
10. The I.V. catheter of claim 9, wherein said catheter is made of a transparent or translucent material.
11. The I.V. catheter of any one of claims 1 to 10, in which the needle guard (30) is self-locking, the needle guard (30) being located about the needle (12) and initially located at the distal end (28) of said needle hub (20).

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